Effects Of Ripening Temperature On The Quality And Expressions Of Quality-formation Related Genes In ’zhongjiao No.9’

Banana is a popular fruit with sweet flesh and rich nutrition.The banana fusarium wilt is easy to spread,and cause huge economic losses to the banana industry.‘Zhongjiao No.9’,a new cultivar resistant to banana fusarium wilt,was selected by institute of fruit tree research,guangdong academy of agricultural sciences.However,there are few studies on physiological characteristics with relation to expressions of quality-formation related genes in ‘Zhongjiao No.9’.Ripening temperature is the most important factors affecting the banana fruit quality,thus,it is worth to exlpore the effects of different temperature conditions on the quality of ‘Zhongjiao No.9’ with relation to the expressions of quality-formation related genes.Using ‘Zhongjiao No.9’ as experimental materials,this study was conducted to explor the effect of temperature on ‘Zhongjiao No.9’ during postharvest by measuring color,chlorophyll,firmness,TSS,starch,soluble sugar and analyzing the expression of related genes of the softening of flesh,the synthesis pathway of aroma and the degradation of starch.The main results were as follows.1.Conventional ripening method(ripening at 22℃)is not suitable for‘Zhongjiao No.9’.Ripening at 22 °C makes the ripening of the peel and flesh of ‘Zhongjiao No.9’ inconsistently,showing that pulp firmness declines faster than the peel-color transformation,ripening at 18 °C can effectively slow down the process of pulp softening,but the TSS and soluble sugar contents in the late ripening stage are lower than those ripened at 22 °C.We found that ripening at 18 °C for two days and then transferred to 22℃ for further ripening,can reduce the decline in the pulp softening and effectively make the peel transformation and pulp softening consistently.Therefore,it is suggested that the suitable ripening method of ‘Zhongjiao 9’ is to ripen at 18℃ for 2 days and then transferred to 22℃ for further ripening.2.The ripening temperature affects the cell wall polysaccharide metabolism and the expressions of starch-degradation related genes of ‘Zhongjiao No.9’: Expressions of Ma EXP1,Ma EXP2,Ma PG1,Ma PG3,Ma XTH5,Ma XTH10,Ma CEL,Ma GWD1,Ma PWD1,Ma ISA3,Ma AMY3,Ma DEP2,Ma BAM2,Ma BAM 3,Ma BAM 7,Ma BAM 8,Ma MEX2,Map Glc T4-1 and Map Glc T4-2 respond to fruit ripening and ripening temperature,of which,Ma EXP2 is one of the most genes affected by temperature during the post-ripening process of ‘Zhongjiao No.9’.3.The ripening temperature affects the expression of the aroma synthesis gene of ‘Zhongjiao No.9’: The expressions of Ma BCAT,Ma ACY,Ma AGT,Ma MT1,Ma OMT,Ma AAT and Ma GT are closely related to the synthesis of aroma substances of ‘Zhongjiao No.9’.The accuulations of these genes are related to the synthesis of esters and the decline of aldehydes.